1. Field of the Invention
The present invention is related generally to a protection switch, or circuit breaker, with a thermal excesscurrent release including at least one bimetallic element.
2. Description of the Related Art
In multi-phase thermal release protection switches, bimetallic elements are each allocated to a respective phase. A free end of each of the bimetallic elements acts on a shared actuation element, which is usually in the form of a slide member. It must be assured by suitable measures that all of the bimetallic elements exert the same force on the actuation element for identical heating. Given a defined ambient temperature and no current flow through the bimetallic elements, the outwardly bending ends of all of the bimetallic elements must be in the same position relative to the actuation element.
To achieve this condition and thereby avoid having to adjust the bimetallic elements in the switch housing after assembly of the protection switch, it has been proposed to form a seating surface on carriers which are provided with the bimetallic elements before insertion into the housing. The seating surface for each of the bimetallic elements proceeds at a right angle relative to a bending direction of the bimetallic elements and at a predetermined identical distance from the deflection ends of the bimetallic elements. A seating surface is disclosed in German Published Application No. 32 24 012.
Cooperating surfaces are formed in the housing, all lying in a common plane. The carriers are secured to the housing with their seating surfaces lying opposite the cooperating surfaces of the housing. It is thus assured that, after complete assembly of the bimetallic elements, the bending ends necessarily assume a position aligned to one another. In this known solution, subsequent adjustment is eliminated, but the manufacturing of the seating surface incurs certain costs.
In German Patent No. 890,207, a protection switch includes a bimetallic element secured to a carrier to form a unit with the bimetallic element. The unit is inserted into a housing part during assembly. The carrier includes arms lying opposite one another and in pairs, which are bent out in a spring-elastic fashion in the bend-out direction of the bimetallic element. When the structural unit formed by the carrier and the bimetallic element is introduced, the arms are resiliently placed against the sidewalls of the housing part so that the unit is held in a defined position. Since the positioning of the structural unit occurs only on the basis of a clamping force, it cannot be assured that the bending end of the bimetallic element assumes a precisely defined position. Thus, additional means must also be provided in order to be able to precisely adjust the bimetallic element after it has been introduced into the housing.